The invention relates to an orienteering compass comprising a distance measuring device including a circular element to be rotated over a map from an arbitrary point A to an arbitrary point B for determining the distance from point A to point B.
The invention also relates to a distance measuring device for an orienteering compass comprising a base plate.
Orienteering in the terrain usually involves using a map and an orienteering compass. A compass enables the orienteerer to find out which direction to take in order to arrive at a desired location in the terrain. In addition to the direction, it is important to know the distance. The distance can be determined by measuring the distance between two arbitrary points on the map using a measuring scale on the orienteering compass and by comparing the measured result with the measuring scale on the map. If an orienteerer takes a course in the terrain that deviates from a direct line, then the distance is difficult to determine in practice, especially if it should be accurately determined. When determining the length of a twisting course the orienteering compass including a measuring scale has to be placed on the map several times so that the measuring scale conforms to the twisting course. Determining the distance is thus slow and cannot be very accurately measured.
It is known to use a distance measuring device in order to facilitate the determination of the length of a course on a map and particularly on a nautical map. Then the distance measuring device can be such that it comprises an axis provided with a thread, along which a rotating element is arranged to move guided by the threads on the axis. When the rotating element is pressed against the map and when it is given the chance to rotate the distance to be traveled, the rotating element moves a certain distance along the axis. It is fairly easy to determine the length of a course by comparing the distance the rotating element has moved on the axis to the measuring scale on the map.
It is also known to use distance measuring devices shaped as pens, the operating principle of which is to measure the rotation of the ball at the tip of the distance measuring device. The ball can roll along the course to be traveled, and the distance measuring device provides a reading on the distance to be traveled. Such a distance measuring device is very useful when the length of a twisting course is measured. However, such a distance measuring device has disadvantages like the high price and the unreliable function when the ball gets dirty, as it then no longer registers the distance reliably.
An orienteering compass including a capsule around which a revolving wheel is arranged is known to facilitate and speed up orienteering. The idea is to press the outer circumference of the wheel against the map so that the outer circumference revolves in relation to the capsule when it rotates against the map. The inner circumference of the wheel then slides against the circumference of the capsule. The length of the travel distance can be determined by letting the outer circumference of the wheel rotate in accordance with the travel distance, the measuring scale on the compass then showing the distance that the wheel has moved and the obtained result is compared with the measuring scale on the map. In principle, this orienteering compass functions very well, but a drawback is that it may provide an incorrect measurement result in addition to that it tends to damage the surface of the map. Said drawbacks are in essence caused by the fact that the inner circumference of the wheel has to be large (correspond to the size of the capsule), thus causing high friction. In order for the wheel to rotate as intended the friction force has to be exceeded, which is why the outer circumference of the wheel is cogged so that the friction against the map surface should be adequate. The cogged surface damages the map surface. If there is no cogged surface or the outer circumference of the wheel is not pressed forcefully enough against the map surface, the outer circumference slides along the map, and naturally an incorrect measurement result is obtained. Another drawback of the prior art orienteering compass provided with a distance measuring device is the large size thereof, caused by the structure comprising a large wheel mounted around the compass capsule. A further drawback is that the distance measuring device tends to break easily; as a protruding part the wheel is easily damaged.